1. Field of the Invention
The present invention relates to a finishing wheel holding mechanism for use in gear finishing apparatuses, such as a honing apparatus and a shaving apparatus, in which a finishing wheel having internal teeth is rotated so as to finish a gear piece in mesh with the finishing wheel.
2. Description of the Related Art
Where a highly accurate tooth profile is required for a gear, finish processing to modify any deformation of the gear having gone through heat treatment, so-called honing, is performed. This finish processing is accomplished by rotating the gear piece to be worked upon in a state in which it is meshed with a finishing wheel having internal teeth at a predetermined crossing angle. The finishing wheel is held by a support gear of a finishing wheel holding mechanism having external peripheral teeth. The support gear is turned by a driving device in mesh with the external peripheral teeth, and is slid by a sliding section for cutting into the gear piece to be worked. Until the correction of the tooth profile is completed, each tooth of the finishing wheel contacts the teeth of the gear piece to be worked repeatedly usually as many as 20 to 200 times. Accordingly, the lifetime of the finishing wheel is generally short.
A typical gear finishing apparatus according to the prior art has only one finishing wheel for each support gear. Therefore, the apparatus has to be suspended from operation every time the finishing wheel has worn out and needs to be replaced with a new one. Fitting a finishing wheel requires not only a high level of dimensional accuracy and careful operation of fitting but also dressing after the fitting to correct errors in the fitting position of the finishing wheel, which are due to inevitable gaps occurring in the fitting work. Therefore, the time taken for finishing wheel replacement constitutes a high proportion of the overall process time of gear finishing, and accordingly its shortening and simplification of the procedure have been called for.
To meet this requirement, the present applicants proposed the gear finishing apparatus described below (Japanese Unexamined Patent Publication No. 7-24634). This gear finishing apparatus holds a plurality of finishing wheels in parallel by a finishing wheel holding mechanism, positions the finishing wheels at a crossing angle relative to a work (gear piece to be worked), and can slide in parallel to the axes of the finishing wheels and fix the work. The finishing wheels are rotated by a driving device fitted to the finishing wheel holding mechanism. The work is held by a pair of tail stocks on the base portion of the gear finishing apparatus. This gear finishing apparatus performs a synchronous operation, in which the work is rotated by a drive motor attached to one of the tail stocks. The finishing wheel holding mechanism is slid in the cutting direction and finishes the work. In this gear finishing apparatus, if the plurality of finishing wheels are fitted to the finishing wheel holding mechanism and positionally adjusted at the outset, a new, already positionally adjusted finishing wheel can be brought to its working position by sliding and fixing the finishing wheel holding mechanism when one of the finishing wheels in use has worn out. Therefore, finish processing can be promptly resumed. Furthermore, by fitting in advance different types of finishing wheels, the preparatory work for a different type of gear piece can be accomplished in a shorter period of time.
However, for the gear finishing apparatus described above, the finishing wheels are usually fixed by fitting a plurality of finishing wheels onto the internal circumferential surface of the finishing wheel holding mechanism, placing a fixing ring as to cover the external end face of the finishing wheel and the end face of the support gear, and fastening fixing bolts which penetrate the fixing ring and the finishing wheels and extendi to the inside of the support gear. Therefore, many fixing bolts have to be fastened along the fixing ring when fitting the finishing wheels. Further, when any of the finishing wheels is to be replaced, those fixing bolts should be loosened and fastened again after the replacement. Although the latter finishing wheel holding mechanism permits prompt resumption of finish processing because a new, already positionally adjusted finishing wheel can be brought to its working position when one of the finishing wheels in use has worn out, the problem of the time and labor consumed in fastening the fixing bolts remains unsolved.
Such problems are not limited to honing but also are commonly encountered in wheel finish processing, such as shaving or the like, using a finishing wheel having internal teeth.
Therefore, an object of the present invention is to provide a finishing wheel holding mechanism for a gear finishing apparatus using a finishing wheel having internal teeth, whose finishing wheel can be fitted and replaced easily and quickly.